Dr Told My Son 7 Years Old Has Insect Bite

Dr told my son 7 years old has insect bite allergy so gave zyrtec syrup and lactocalamine lotion so that his mild redness will fade and eventually vanish. Somebody suggested me dettol wash. I used concentrated dettol wash on his penis area as that was showing more redness. It's swollen now, any home based remedy or I need to show to dermatologist or pediatrician.